OMAHA (DTN) -- EPA has been ordered to cancel chlorpyrifos registrations within 60 days, after the U.S. Court of Appeals for the Ninth Circuit in San Francisco ruled on Thursday the agency was not justified in maintaining the insecticide's registration "in the face of scientific evidence that its residue on food causes neurodevelopmental damage to children."

The EPA denied a petition filed by environmental groups on March 30, 2017, to ban the pesticide outright. The agency said in a statement at the time that farmers need chlorpyrifos and an agency that relies on "sound science" when making decisions.

That move was a surprising reversal from the stance of the EPA under the previous administration, which had indicated as recently as fall 2016 that it was prepared to issue a full ban on the pesticide.

Chlorpyrifos is the main ingredient in Dow AgroSciences' Lorsban insecticide, which targets pests such as soybean aphids, spider mites and corn rootworm.

The legal pursuit began in 2007 when the Pesticide Action Network North America and the Natural Resources Defense Council petitioned EPA to cancel chlorpyrifos registrations.

"Despite these earlier expressions of concern, the EPA failed to take any decisive action in response to the 2007 petition," the Ninth Circuit said in its ruling, "notwithstanding that the EPA's own internal studies continued to document serious safety risks associated with chlorpyrifos use, particularly for children."

Judge Jed S. Rakoff said in his opinion the EPA has been delaying a decision, although its own science points to health risks in children who eat food that contains chlorpyrifos.

"Yet, over the past decade and more, the EPA has stalled on banning chlorpyrifos, first by largely ignoring a petition properly filed pursuant to law seeking such a ban, then by temporizing in response to repeated orders by the court to respond to the petition; and finally, in its latest tactic, by denying outright our jurisdiction to review the ultimate denial of the petition, even while offering no defense on the merits," Rakoff writes.

"If Congress's statutory mandates are to mean anything, the time has come to put a stop to this patent evasion."

DATA QUESTIONED

EPA Spokesperson Michael Abboud said the Ninth Circuit made a decision based on data that has not been accessible to the agency.

"EPA is reviewing the decision," he said. "The Columbia Center's data underlying the court's assumptions remains inaccessible and has hindered the agency's ongoing process to fully evaluate the pesticide using the best available, transparent science."

The Columbia Center for Children's Environmental Health study has been widely used as support for a ban, despite divergent scientific views among EPA scientific review panels and President Barack Obama's administration's USDA questioning the study and its data.

A 2016 EPA scientific advisory panel indicated some members of that panel said they had difficulty assessing the study, because the raw data from the study was not made available.

In a January 2017 letter from USDA to EPA, USDA expressed concerns about the science EPA was using. As a result of that concern, EPA denied a petition from environmental groups to cancel chlorpyrifos registrations.

"USDA has both grave concerns about the EPA process that has led to the agency publishing three wildly different human health risk assessments for chlorpyrifos within two years, and severe doubts about the validity of the scientific conclusions underpinning EPA's latest chlorpyrifos risk assessment," the letter said.

Erik Olson, senior director of health and food at the Natural Resources Defense Council, said in a statement to DTN the ruling was important for children's health.

"Some things are too sacred to play politics with, and our kids top the list," he said. "The court has made it clear that children's health must come before powerful polluters. This is a victory for parents everywhere who want to feed their kids fruits and veggies without fear it's harming their brains or poisoning communities."

On July 30, 2018, the California Department of Pesticide Regulation released a scientific assessment that concluded that chlorpyrifos should be listed as a toxic air contaminant in the state based on evidence of its neurological effects and exposure risks of concern.

BAN CONCERN

Agricultural groups had expressed concern over a ban, arguing that doing away with chlorpyrifos could complicate the battle against insects, especially when growers are being encouraged to rotate chemistries to guard against insect resistance. A number of industry groups, such as CropLife America, the National Corn Growers Association and the American Soybean Association, celebrated the March 30 EPA decision not to revoke the pesticide, which plays a significant role in corn and soybean pest control.

Corn accounts for chlorpyrifos' largest agriculture market as far as total pounds used, because overall, there are more corn acres than soybean acres, according to EPA. However, in recent years, use of chlorpyrifos has expanded in soybeans and has been on the decline in corn.

According to Dow AgroSciences' website, chlorpyrifos use in soybeans expanded from about 200,000 acres in 2004 to about 8 million acres in 2008. Dow estimated chlorpyrifos was applied to about 11% of soybean acres planted in 2008.

The road to the proposed chlorpyrifos ban began when the Pesticide Action Network North America and Natural Resources Defense Council filed a petition in 2007 to force EPA to take action on chlorpyrifos, based on concerns over drinking water. In June 2015, the Ninth Circuit issued a ruling pressuring EPA to make a decision by Oct. 31, 2015, on whether or not it would establish food tolerances for the insecticide. EPA stated it did not have the data needed to do so and instead would pursue a ban.

EPA asked the court for a six-month extension to take final action. In a final order issued Aug. 12, 2016, the court ruled against the request by EPA and ordered the agency to take action by March 31, 2017.

Most recently, the EPA revised its human health risk assessment for chlorpyrifos in November 2016 to state that residues on food crops and in water are at unsafe levels.